Regeneration is not a simple repetition of development

Publication of the IGFL in the journal PNAS . CNRS-INSB communication on July 12, 2022. Some organisms have the fascinating capacity to regenerate lost body parts. To which extent regeneration entails the redeployment of an embryonic developmental program is a long-standing question of regenerative studies, with implications for development, evolution, and regenerative medicine. In this study, we address this question by comparing the global transcriptional dynamics of leg regeneration and leg development in the crustacean Parhyale hawaiensis . We show that despite extensive overlaps in gene usage, the development and regeneration of Parhyale legs show distinct temporal profiles of gene expression that cannot be aligned in a coherent fashion. These results suggest that regeneration does not simply mirror development, but deploys some of the same gene modules in a different overall framework.